使用 asp.net 发送电子邮件显示此错误：SMTP 服务器需要安全连接或客户端未通过身份验证

Question

I try to send email using this code:

  public void Semail(string subject, string messageBody, string toAddress)
        {
            MailMessage mail = new MailMessage();
            mail.To.Add(toAddress);
            //mail.To.Add("amit_jain_online@yahoo.com");
            mail.From = new MailAddress("noreplykaramaoozi@eesharif.edu");
            mail.Subject = subject;
            string Body = messageBody;
            mail.Body = Body;
            mail.IsBodyHtml = true;
            SmtpClient smtp = new SmtpClient();
            smtp.Host = "sina.sharif.ir"; //Or Your SMTP Server Address
            smtp.Port = 587;
            smtp.Credentials = new System.Net.NetworkCredential
                ("noreplykaramaoozi@eesharif.edu", "*******");
            //Or your Smtp Email ID and Password
            smtp.EnableSsl = false;
            smtp.Send(mail);
        }

But after executing i got this error:

 The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.0 Authentication required 

Stack Trace :

[SmtpException: The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.0 Authentication required]
   System.Net.Mail.MailCommand.CheckResponse(SmtpStatusCode statusCode, String response) +2162008
   System.Net.Mail.MailCommand.Send(SmtpConnection conn, Byte[] command, String from) +287
   System.Net.Mail.SmtpTransport.SendMail(MailAddress sender, MailAddressCollection recipients, String deliveryNotify, SmtpFailedRecipientException& exception) +137
   System.Net.Mail.SmtpClient.Send(MailMessage message) +2188821
   Novitiate.fa.Register.btnLogin_Click(Object sender, EventArgs e) +2948
   System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +154
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3707

Best regards

Answer 1

Your gmail security preventing the message to access the gmail account. So,if you want to send the message you have to "turn off" the access for less secure app. When you do this you can easily send the message but, by risking your gmail security. So, it is upto you this definitely work.

link for changing security is given below

https://www.google.com/settings/security/lesssecureapps?pli=1

Answer 2

Try this one if this helps:

MailMessage mail = new MailMessage();
SmtpClient SmtpServer = new SmtpClient("smtp.gmail.com");
mail.From = new MailAddress(Username);
mail.To.Add(TxtEmail.Text);
mail.Subject = Subject;
mail.Body = Body;
SmtpServer.Port = 587;
SmtpServer.Credentials = new System.Net.NetworkCredential(Username, Password);
SmtpServer.EnableSsl = true;
SmtpServer.Timeout = 20000;
SmtpServer.Send(mail);

Answer 3

登录到您的电子邮件帐户后，请考虑 @Krunal Patil 在那里的回答，并对发送的验证邮件进行操作以授予对您的 C# 应用程序的访问权限。